This invention relates to a cassette loading mechanism for a magnetic disk device using a disk cassette to effect magnetic recording in which mechanism a disk cassette is moved up and down between a temporary loaded position and a final loaded position.
A typical one of cassette loading devices for conventional magnetic disk devices of the type described above is illustrated in FIGS. 1 to 3.
Referring to FIGS. 1 to 3, reference numeral 1 denotes a disk cassette in which a flexible disk 2 is accommodated as seen in detail in FIG. 4, 10 a magnetic disk device onto which the disk cassette 1 is to be inserted or loaded, 11 a chassis of the disk device 10, 12 a drive motor secured to a bottom face of the chassis 11 and having a driving portion exposed to a top face of the chassis 11, 13 a spindle hub provided on the driving portion of the drive motor 12, 14 a positioning pin provided on the spindle hub 13 for engagement with a hole 3 of the disk cassette 1 shown in FIG. 4, 15 a driving pin also provided on the spindle hub 13 for engagement with another hole 4 of the disk cassette 1 shown in FIG. 4, 16 a panel provided on a front face of the chassis 11, 17 an opening formed in the panel 16 for allowing a disk cassette to be loaded onto and unloaded from the magnetic disk device, 18 a guide rod provided on the top face of the chassis 11, 19 a carriage supported on the guide rods 18 and connected to be driven by a driving means to be mentioned below, and 20 a positioning driving means for the carriage 19. The positioning driving means 20 includes, as shown in FIG. 3, a drive pulley 21 on a positioning motor (not shown) secured to the bottom face of the chassis 11, an idler pulley 22, and a belt 23 extending between the drive and idler pulleys 21 and 22 and coupled to the carriage 19.
Reference numeral 24 denotes a first magnetic head mounted on the carriage 19, 25 an arm mounted for pivotal motion of the carriage 19 by means of a fulcrum pin 26, 27 a second magnetic head mounted on the arm 25, and 28 a lifting portion extending from an intermediate portion of the arm 25 for lifting the arm 25. The function of the lifting portion 28 will be hereinafter described.
Reference numeral 29 denotes a disk cassette holder for guiding a disk cassette 1 to be loaded and for holding it thereon, and when a cassette is not loaded, the disk cassette holder 29 is positioned in opposing relationship to the opening 17 of the panel 16, and when a cassette is to be loaded, the disk cassette holder 29 is moved down to position the disk cassette 1 to a position as shown in phantom in FIG. 5. The disk cassette holder 29 is supported on a movable plate 33 having a structure as hereinafter described. Reference numeral 30 denotes a bent lug formed on either of opposite side edges of the disk cassette holder 29, 31 a pin secured to each of the bent lugs 30, 32 a roller mounted for rotation on each of the pins 31, and 33 a movable plate provided on the chassis 11 for movement in a direction of an arrow mark in FIG. 3. The movable plate 33 has a pair of bent portions 34 located outwardly of opposite sides of the disk cassette holder 29, and an inclined groove 35 is formed on a portion of each of the bent portions 34 of the movable plate 33 corresponding to one of the rollers 32 so that the roller 32 may engage with the inclined groove 35. Thus, the holder 29 is supported by engagement of the rollers 32 with the inclined grooves 35. Reference numeral 36 designates an operation button provided on the movable edges of the top face of the chassis 11 and located outwardly of the bent portion 34 of the movable plate 33. Each of the brackets 37 has a guide groove 38 formed therein which is engaged with one of the pins 31 so as to allow the roller 32 engaged with the inclined groove 35 of the bent portion 34 of the movable plate 33 to effect only up and down movement as the movable plate 33 moves. With this construction, when the movable plate 33 moves in a direction of arrow A toward the bottom of FIG. 3, the holder 29 is lowered to approach the chassis 11 by the inclined grooves 35, and on the contrary when the movable plate 33 moves in the opposite direction of arrow A toward the top of FIG. 3, the holder 29 is lifted.
Reference numeral 39 denotes a lever portion provided at a rear part of the disk cassette holder 29 for transmitting a motion of the holder 29 to the lifting portion 28 of the arm 25 to control pivotal motion of the arm 25, 40 a stopper portion formed at another rear part of the disk cassette holder 29 for abutting engagement with a disk cassette 1 loaded in the magnetic disk device, 41 a lock pin provided at part of the movable plate 33, and 42 a lock level mounted for pivotal motion on the chassis 11 by means of a pin 43. The lock lever 42 has an engaging shoulder 44 formed to engage with the lock pin 41, and a cassette detecting pin 45 located to be pushed by a disk cassette 1 slightly before the disk cassette 1 is abutted with the stopper portion 40, and is acted upon by a force to pivot the same in a clockwise direction in FIG. 3 by means of a spring 46. Reference numeral 47 designates a return spring for returning the movable plate 33 in a direction of arrow mark toward the bottom of FIG. 3 to an initial position. When a disk cassette 1 is not loaded in the magnetic disk device, the lock pin 41 is in engagement with the engaging shoulder 44 of the lock lever 42 so that the movable plate 33 is prevented from being moved or returned in the direction of arrow mark toward the bottom of FIG. 3 by a force of the return spring 47.
Reference numeral 48 in FIG. 2 designates a holding spring secured to the holder 29 for holding a disk cassette 1 downwardly toward the chassis 11, and reference numerals 49 and 50 in FIG. 3 denote each a positioning pin for receiving thereon a disk cassette 1 which has been lowered together with the holder 29.
Operations of the magnetic disk device will be described now.
The disk device having such a construction as described above has a basic structure which, after a disk cassette 1 as shown in FIG. 4 has been inserted in a direction Y from an insertion position indicated by H1 in FIG. 5, lowers the disk cassette 1 and positions it to a position H2.
A disk cassette 1 is inserted through the opening of the panel 16 into the disk cassette holder 29 until it is abutted with the stopper portion 40 provided on the disk cassette holder 29. A little before the disk cassette 1 is abutted with the stopper portion 40, the detecting pin 45 of the lock lever 42 which is in engagement with the lock pin 41 on the movable plate 33 is pushed by the disk cassette 1 to pivot the lever 42 to disengage the engaging shoulder 44 thereof from the lock pin 41 (FIGS. 6(a) and 6(b)) so that the movable plate 33 is allowed to be slipped by a force of the return spring 47 in a direction toward the panel 16 to a position as indicated by a position of the button 36 which is shown by a broken line in FIG. 1.
By this slipping movement of the movable plate 33, the disk cassette holder 29 is lowered with the disk cassette 1 carried thereon due to engagement of the inclined grooves 35 of the bent portions 34 of the movable plate 33 with the rollers 32 on the cassette holder 29. As the disk cassette holder 29 is lowered in this way, positioning holes 5 and 6 (FIG. 4) provided in the disk cassette 1 are fitted around projection 49a (FIG. 5) of the positioning pins 49 to thereby position the disk cassette 1 in X--X and Y--Y directions. Meanwhile, the disk cassette 1 is positioned in the Z direction to a plane defined by the positioning pins 49 and 50. Thus, the flexible disk 2 is positioned and rotated by the positioning pin 14 and the drive pin 15 on the spindle hub 13 which pins are fitted in the holes 3 and 4, respectively, formed at a central part of the flexible disk 2.
As the cassette holder 29 is lowered, the arm 25 is pivoted in a counterclockwise direction in FIG. 1 about the fulcrum pin 26 by an arm pressing spring (not shown) until the second magnetic head 27 which has been spaced from the first magnetic head 24 due to engagement of the lifting portion 28 of the arm 25 with the lever portion 39 of the disk cassette holder 29 is lowered into contact with the first magnetic head 24 via the flexible disk 2. It is to be noted that the lever portion and the lifting portion are spaced from each other in a completely lowered position of the disk cassette holder 29. This intends to stabilize recording/reproducing operations of the magnetic disk device by providing a slight gap between the lever portion 39 and the lifting portion 28 upon recording/reproducing operation.
When the disk cassette 1 is to be unloaded from the magnetic disk device, the button 36 which is projected to the broken line position in FIG. 1 will be pushed in the disk cassette inserting direction. As the button 36 is thus pushed in, the movable plate 33 coupled to the button 36 is also pushed against the returning spring 47 to slip to a predetermined position at which the lock pin 41 on the movable plate 33 is engaged again with the lock lever 42. Consequently, the movable lever 33 is held to the predetermined position by the lock lever 42. Meanwhile, the disk cassette holder 29 is lifted by the rollers 32 engaged by the inclined grooves 35 of the movable plate until the initial position in which a disk cassette 1 can be loaded or inserted into the device is reached to allow the disk cassette 1 to be discharged by means of an ejector not shown. In the meantime, as the holder 29 is lifted, the arm 25 is pivoted by the lever portion 39 engaged with the lifting portion 28 so that the second magnetic head 27 is moved out of contact with the first magnetic head 24 to a position in which the disk cassette 1 is prevented from interfering with the second magnetic head 27 when it is discharged from the device.
As described above, in the cassette loading mechanism for lifting and lowering a disk cassette between a temporary loaded position and a final loaded position, loading or inserting operation of a disk cassette 1 will cause, simultaneously with such insertion, collision of the first and second magnetic heads 24 and 27 with each other via a flexible disk 2 before they are brought into normal contact with each other via the flexible disk 2. A colliding force in this case originates in a force of the return spring 47 for the movable plate 33, and hence such collision occurs when a slipping speed of the movable plate 33 is at its maximum, or in other words, when a colliding force of the second magnetic head is at its maximum. As a result, a record face of the flexible disk 2 is sometimes damaged to disable recording to and/or reproduction from the same, or else the first and/or second magnetic heads are sometimes broken. The cassette loading mechanism has another drawback that if a force of the return spring 47 for the movable plate 33 is reduced to reduce the colliding force, operation itself of the movable plate becomes unstable.